Tandem-type electro-photographic color printers are well known in the art. A tandem-type color printer has four photosensitive drums for the colors yellow, magenta, cyan, and black, for example, the four photosensitive drums being disposed parallel to one another in a tandem arrangement.
The color printer includes a main frame, a drum support unit, and a scanner unit. The main frame is made from a metal and has a pair of side wall portions confronting with each other. The drum support unit is movable relative to the main frame for supporting the photosensitive drums of respective colors. The scanner unit is positioned above the drum support unit and is supported to upper end portions of the side wall portions for irradiating light to the respective photosensitive drums.
A positioning member extends between the rear end portions of the side wall portions, and an insertion groove is formed at each front end portion of each side wall portion. The drum support unit has a front end portion formed with a positioning recess engageable with the positioning member, and has a rear end portion provided with a linking member. The linking member has protruding end portions engageable with the insertion grooves. Thus, the drum support unit can be positioned relative to the main frame.